MUZAFFARABAD, Pakistan — With snow falling in parts of Kashmir, harried relief workers tried to reach remote areas on foot Thursday as the U.N.’s emergency relief chief warned time was running out for many survivors of South Asia’s massive earthquake.

U.N. Undersecretary General and Emergency Relief Coordinator Jan Egeland flew by helicopter to the Kashmiri city of Muzaffarabad, where he said millions of people urgently needed food, medicine, shelter and blankets. The U.N. estimates 2 million people are homeless ahead of the Himalayan region’s fierce winter.

“I fear we are losing the race against the clock in the small villages” cut off by blocked roads, Egeland said. “I’ve never seen such devastation before. We are in the sixth day of operation, and every day the scale of devastation is getting wider.”

The plea came after a 5.6 magnitude aftershock jolted parts of Pakistan early Thursday, forcing a rescue team to suspend efforts to save a trapped woman. She died before the rescuers returned to the precarious rubble.

The quake death toll was more than 35,000, and tens of thousands were injured. India has reported more than 1,350 deaths in the part of disputed Kashmir that it controls.

Carrying water, juice and milk, a relief team from Britain-based Plan International flew in a helicopter to villages in northern Mansehra district in North-West Frontier Province and found death and misery.

“Conditions are going from bad to worse. These people don’t have any shelter. Also the school has collapsed, and the children were in those class rooms,” he said.

Ahmed said one elderly survivor was evacuated with a semiconscious 3-year-old boy who was barely moving, his skin cold and clammy.

Another Britain-based group, ActionAid International in Pakistan, said its workers tried to reach remote mountainous areas, but had to walk in one area because of bad roads and traffic jams.

“The problem is that people are facing a shortage of time,” said Shafqat Munir, a spokesman for the group. “It’s cold, raining. People are without shelter. They have food, clothes, blankets, but tents are a problem.”

The 5.6 magnitude aftershock early Thursday was centered 85 miles north of Islamabad, near the epicenter of Saturday’s 7.6 magnitude quake that demolished whole towns, mostly in Kashmir and northwestern Pakistan. The aftershock shook buildings, but there was no significant damage in the demolished region.

“People were scared. Even those who were sleeping in tents came out. Everybody was crying,” said Nisar Abbasi, 36, an accountant camping on the lawn of his destroyed home in Muzaffarabad, capital of Pakistan-controlled Kashmir.

A 22-year-old woman detected by a sniffer dog in the rubble in Muzaffarabad died after the aftershock forced rescue teams to suspend their efforts, rescuers and witnesses said.

When they returned after daybreak, the sniffer dog whined, indicating it detected the smell of a corpse. Some rescue workers wept.

“It was a very difficult decision to leave a living person and I had a responsibility to my team. It could have meant their death,” said Steff Hopkins, a British team leader.

A milder aftershock hit the same area Thursday night, with no immediate reports of damage, according to Pakistan’s state-run seismological center in the northwestern city of Peshawar.

There have been dozens of aftershocks since the main quake. Experts said they could go on for months.

In Muzaffarabad, relief workers wrapped 35 bodies in shrouds and carried out a mass burial Thursday. The burial was coordinated by Jamat-e-Dawad, a group linked to Islamic militants that is operating dozens of ambulances in the city and running a camp for quake victims.

Earlier this week, the U.N. launched an international appeal for $272 million for six months of emergency aid to Pakistan. Yvette Stevens, a U.N. relief coordinator in Geneva, said about $165 million of aid had been pledged as of Thursday. Some 30 nations have contributed relief supplies and manpower.

The U.S. military in Afghanistan loaded cargo planes with food, tarpaulins and other emergency aid to begin dropping by parachute over areas of Pakistan on Friday, officials said.

An Indian plane has also delivered aid to Pakistan despite the rivalry between the two countries, which have fought three wars, two of them over Kashmir.

But the Kashmiri conflict continued unabated. Police in Indian-held Kashmir said a woman suicide bomber blew herself up Thursday near an army convoy. A militant group said five soldiers died, but police denied it.

Nearly a dozen Islamic rebel groups are fighting for Kashmir’s independence from India or its merger with Pakistan. Tens of thousands have died.

Otto Warmbier was arrested in January 2016 at the end of a brief tourist visit to North Korea. He had been medically evacuated and was being treated at the University of Cincinnati Medical Center when he died at age 22.